Allogeneic hematopoietic stem cell transplant has the potential to cure various hematological malignancies and inherited disorders but is limited by treatment-related mortality, which in a majority of cases is directly related to Graft-versus-Host Disease (GVHD). Current therapy for GVHD involves prolonged immunosuppression with calcineurin inhibitors such as cyclosporine and tacrolimus. However, in itself prolonged immunosuppression results in delayed immune function leading to infectious complications as well as a risk of post-transplant lymphoproliferative disorders. Thus, there is a clear need for alternative approaches to mitigate the deleterious effects of GVHD whether acute or chronic. With proof-of-concept preclinical studies completed, we are requesting funding to support a pilot two- stage Phase I/IIa safety and preliminary efficacy clinical trial investigating an innovative cell-based approach for prevention of GVHD in a dual cord blood transplant setting. Our proposed approach is novel in that it capitalizes on the beneficial and well-established anti-inflammatory effects of systemically administered regulatory T cells (Tregs) combined with enhanced homing/engraftment following their ex vivo treatment with TZ101. TZ101 is comprised of the enzyme ? 1, 3 fucosyltransferase (FTVI) and its substrate, guanosine diphosphate-fucose which, when incubated with cells, leads to site and stereospecific addition of fucose to cell surface glycoproteins. This has been shown by a number of different Investigators to enhance selecting- mediated binding for varying cell types. Most notably, this interaction underlies the homing of stem/progenitor cells to sites of upregulated levels of selectins which is a hallmark of inflamed tissue. A search on clinical trials.gov for regulatory T cells reveals over 400 clinica trials, demonstrating the importance and safety of administration of this immune population. Furthermore, T-regs are endowed with multiple features that can clearly address GVHD across a broad patient population, such as: lack of stimulation of a proliferative response from alloreactive T-cells, alteration of cytokine secretion profile of dendritic cells, T cells and natual killer cells in vitro, inhibition of secretion of proinflammatory cytokines and increased expressio of suppressive cytokines. We are proposing four specific aims: 1) Production of cGMP TZ101 reagents (FTVI and GDP-fucose) 2) Phase I: examination of the safety of dose level 1: fuocsylated T-regs at 1x106 /kg patient weight. We will use three co-primary outcomes measures for safety: 1) time to severe infusional toxicity, 2) grade 3, 4 GVHD and 3) death. 3) Phase IIa: examination of preliminary efficacy at a single dose of fucosylated T-regss at 1x107 cells/kg patient weight. We will use the primary outcome T = the time to severe (grade 3 or 4) GVH to death, monitored over the first 100 days post allotransplant for efficacy 4) Preclinical in vitro and in vivo studies pursuing the mechanism of action of fucosylated Tregs along with correlating in vivo outcome measures with ongoing clinical results The results from these proposed studies will provide us with sufficient information to assess the merits of advancing this cell-based approach for GVHD into a Phase IIb multicenter trial. If ultimately successful, availability of fucosylated Tregs will provide additional options in the clinical management of GVHD for better patient recovery and improved quality of life. Furthermore, it will stimulate exploration of this promising new cell therapeutic approach for application with autoimmune and other diseases.